"Now THAT is a #10YearChallenge Be authentic to yourself," Jenner wrote.
"Time sure does fly when you are having fun!! #10YearChallenge," Witherspoon posted.
Miley Cyrus & Liam Hemsworth
Newlywed Cyrus instagrammed this adorable pic of her with her new husband.
Jeffree Star (ft. Miley Cyrus)
"Myself and the legend @mileycyrus ❤️ #2009 #iconic
Peep her #Redbull.. back then so many people were mad she was drinking an energy drink in this photo. I think we both turned out alright.. 😇," Star wrote.
We're thinking JLo just gets better with age!
Chrissy Teigen & John Legend
A baby-faced Teigen called her husband ageless. Doesn't he look the same though?!
While we can barely see the age difference, DeGeneres noticed something more intricate:
"I never realized how differently I hold my hand now."
Hilarious as always, the "I Feel Pretty" actress uploaded the below images.
Jackson took to Instagram to share the sweetest throwback photo with fan and pal Keshia Knight Pulliam.
James Van Der Beek
If you thought that a heartthrob Dawson couldn't get better with age, you were wrong!
And although she's not technically a celebrity, Schapelle Corby's #10yearchallenge also had to make an appearance.